HELP! Severe acceleration lag

DIGItonium

If you've concluded that the switch is faulty, get it replaced. What I wanted to do in the past was rig up an LED to indicate switch status and eventually to a datalogger to plot the switch state to see if it's intermittent.

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juld0zer

thing is, i've tested the switch itself and it seems to be fine on the bench hooked up to a multimeter so i'm thinking it's an adjustment issue.

for the LED indicator thing, since the switch is normally open when the brake pedal is pressed then it would be simple to wire a lamp so the lamp comes on when pedal is at rest

esfourteen

this did not fix my issue unfortunately, I disabled ETC once again until I can think of something else to try

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Build Thread | GTM TT Install Thread | Engine Build Thread

juld0zer

so the joy brought by the paperclip trick was short lived. on long drives, the problem eventually resurfaces but this still tells me i am on the right track to solving this issue.

i removed the paperclip and refitted the cruise control brake switch and also the brake light switch. i read further into the issue in the FSM and there's a section that basically states the cruise control switch must be depressed first, which then switches on the brake light switch circuit. Sounds bizarre and far too complex for a simple system to be honest. But anyway, with that in mind i set out to adjust the two switches so the cruise switch trips first. Remember that this is a normally open switch (open circuit when not depressed).

i took it for a drive last night and the f**king issue came up again!!

my mind is now focussed on the soft plastic grommets/button pad things on the brake pedal which press on the switches' plungers. since it's winter here (a much colder winter than last) i usually have the heater on max with the air directed at my face and feet.

I'd like to also mention here that my heater never felt effective. It was either super hot or luke warm... until i recently did the throttle body coolant bypass mod (complete removal of all associated rubber hoses) which seemed to restore function to the temperature modulation function.

My new theory is that the heater aimed at my feet is heating up the plastic grommets to the point where they become pliable enough to allow the switches' plungers to deform the grommet and create a false pedal-depressed situation. Extreme view, but i'm losing my head over this issue

DIGItonium

That's why I added a shimmy.

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juld0zer

time to put the thinking cap on..

i want a more permanent solution

DIGItonium

If the switch is still operational you can loosen the nut holding the switch and try to lower it. Otherwise, you can add a shimmy. You can also replace the grommet with something a little thicker. Lastly, bypass it altogether, but there are risks.

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juld0zer

the paperclip was the bypass it works but the ECU eventually figures something is sus and kills the party. it's a good get you home trick though and it might work for those who want to light up the rears/do standing launches in their 7AT.

risk IMO for this trick is minimal unless the driver uses cruise control frequently.

i'll look into a nylon object but we'll see how my hunt goes. thanks again mate.
are you still getting the lag randomly these days or have you completely cured it?

juld0zer

after much f**king around, i conclude that neither of my brake switches are faulty.

I finally decided to follow the crank and cam angle sensor route today, pulled out the crank angle sensor (absolute bitch because the bolt is not visible, side of the gearbox is sharp/coarse and it's right near the cat). Done the resistance tests and it is defective as per the FSM.

Pin 1 (+) to 2 (-) : 1.117k ohm
Pin 1 (+) to 3 (-) : infinity ohm
Pin 2 (+) to 3 (-) : infinity ohm

All readings should be anything but zero or infinity ohms. I always thought with resistance checks, polarity of the test leads should not matter. If i connect the test leads in reverse, all readings show the sensor is ok so be sure to check the polarity of your test leads when doing these checks.

For kicks, i also checked both cam sensors. Both failed for the same reasons....

Looks like it's a dealer visit for this one. Still no codes either....

esfourteen

interesting, I'll try to check these this week as well

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Build Thread | GTM TT Install Thread | Engine Build Thread

juld0zer

the crank angle sensor is very annoying to get to. i have small hands and at this rate i will be referred to a psychiatrist from all the scratches and cuts on the back of my hands! there's not much room to work in.

cam sensors are really easy - at the front of the engine. you can do the checks without removal but the engine should be cold because the service manual specifies @ 25*c

L33T Z34

Yeah, that crank sensor is a Bee0tch to get to. I can't imagine removing it w/the OEM cats installed.

Did you reflash the ECU back to the OEM ROM and see if the problem persists

juld0zer

still running the tuned throttle tables. i dont think uprev is the cause because the problem only seems to appear when the engine gets up to operating temp. it's still a variable which i will explore when i get my car back.

juld0zer

i got my car back from the dealer.
i had a list lf warranty issues to fix:
- boot doesnt release on first press (new hatch springs fitted)
- boot struts provide little assistance at upper half of travel (new struts fitted)
- ac/volume controls are jittery (control panel backordered from japan)
- clutch fluid disappearing (slave cyl replaced)
- severe lag when at operating temp...

i took the tech for a test drive when i picked up the car. they blamed my stillen intakes but i argued. they said the cam and crank sensors are fine even though i pointed them to the exact page in the service manual.

the fault did occur during the test drive. tech tried to mask it by demonstrating that it 'is normal' by driving aggressively (launching at 2500-3000+ rpm and keeping revs above mid range). i pointed this out that the car shouldnt have to be driven like that all the time. he took the car into the workshop and brought it back out for me to drive home and monitor its progress.

i have to say, whatever happened in the workshop prior to me taking the car home seems to have cured it. i cant seem to make it happen. i've crawled home thru traffic a few times, driven it hard and gently. so far so good. rpm still sags to 500rpm at idle sometimes.

as for the slave cyl, my clutch feels better than the day i picked up the car 2nd hand with 15000km on the clock! pedal is heavier but has more feel. gearshifts are really smooth. 1st to 2nd no longer clunks. rev match is pretty much flawless.

let's see how she goes

P's_Z

Good for you juld0zer! I should be taking mine in sometime the following week, things at work have been hectic but hopefully i can get Monday off.

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Zeta